This application claims the benefit of Japanese Application No. 2000-60868 filed in Japan on Mar. 6, 2000, the entire disclosure of which is incorporated by reference.
1. Field of the Invention
This invention concerns an image calibration device and image calibration method for a multi-display device which combines and displays on a screen the projected pictures of a plurality of projectors, and in particular concerns an image calibration device and image calibration method capable of accurate image calibration of the projected picture of a multi-display device.
2. Description of the Related Art
In recent years, with the growing screen sizes of display devices, there has been interest in projectors which display pictures on screens by enlargement and projection.
Such projectors include, for example, liquid crystal projectors in which a picture is displayed on a liquid crystal panel based on input image signals, and by enlargement and projection, this picture is displayed on a screen. Due to the thin shape, light weight, low driving voltage, and low power consumption of the display device, liquid crystal projectors are currently the mainstream of such display devices.
Due to recent demands for increased screen sizes, so-called multi-display devices, which enable the display of large-screen pictures by combining a plurality of the above projectors, have come into use as, for example, displays for corporate advertising and various events.
In general, multi-display devices are either devices comprising a plurality of projectors accommodated by a housing and a single screen, or so-called cube-type devices in which a projector and screen set make up a single device, a plurality of which are combined in, for example, a 2xc3x972 configuration, positioning four such sets as a single display device. Other devices are front-projection-type devices in which a plurality of projectors are provided in a row, for enlargement and projection onto a single screen.
However, in the above-described multi-display device, because a picture is displayed on a large screen, measures to increase the definition of the projected image are essential, and in the past a variety of proposals have been made. For example, in a proposal described in Japanese Patent Laid-open No. 9-326981, a method to obtain high-definition projected pictures is proposed as a picture projection system.
Specifically, the picture projection system comprises means to generate high-definition picture data, picture projection means having a plurality of projectors to project at least part of the above high-definition picture data, and picture processing means to select and process at least part of the above high-definition picture data for output to the above plurality of projectors.
In such a picture projection system, a projection method is executed in which the above picture projection means is used to partially overlap the pictures of each projector to form a single large picture, and moreover picture processing is performed by the above picture processing means such that the overlapping parts of the picture are smoothly connected. To this end, first a digital camera or other picture-taking means takes a picture of reference pictures projected onto the screen by each projector, to capture the positions, colors, brightnesses, and other parameters of each picture. Thereafter, these parameters are referenced to perform calibration processing of the original picture by picture processing means within a personal computer, and smooth connection of projected pictures is achieved by output to each projector. By this means, projected pictures with higher definition are possible.
In the case of the above-described cube-type device, at the time of installation, for example, differences in brightness and color between four devices are calibrated to bring them into coincidence, to raise the definition of the projected picture. In front-projection type devices also, similar to cube-type devices, by executing a calibration method, smooth connections between projected pictures are achieved.
However, in the processing method of the above-described conventional picture projection system and calibration method of cube-type and similar devices, when such processing is executed for a multi-display device installed indoors, for example, in order to project or calibrate colors and brightness more accurately, it has become necessary to darken the room and shut out external light, in order that, there by no adverse effects of ambient external light on image calibration.
However, there are cases in which sunlight cannot be blocked, or in which other persons in the same room are performing some task and cannot extinguish lights within the room. In such cases, the ambient external light adversely affects image calibration, resulting in the problem that a satisfactory high-definition projected image cannot be obtained. This problem is particularly marked when a multi-display device is installed outdoors, and cannot easily be solved.
Further, in conventional multi-display devices it is desirable that, at the least, a clean screen be used for accurate execution of the above-described image calibration processing. Consequently the screen surface must be cleaned. However, there is the added problem that such cleaning has conventionally entailed complex tasks, and has been troublesome.
As explained above, in conventional picture projection systems and multi-display devices, when it is not possible to shut out external light adversely affecting image calibration, for example, if, when installing a multi-display device indoors, it is not possible to block out sunlight, or if other persons are performing tasks in the same room and lights in the room cannot be extinguished, the ambient external light adversely affects image calibration, and as a result satisfactory high-definition projected images cannot be obtained. Such problems are especially prominent when a multi-display device is installed outdoors, and resolution of such problems is extremely difficult.
This invention was devised in light of the above problems, and has as an object the provision of an image calibration device and image calibration method which is capable of blocking out external light in the vicinity of the device, which is of simple construction, and which is capable of accurately performing image calibration processing.
The image calibration device of this invention is an image projection device which projects a plurality of images onto different positions on a screen by means of a plurality of image projection devices (projectors), and which calibrates the image by using an image pick-up device to take a picture of the image on the screen formed in this way, and which is characterized in comprising a shielding member, provided so as to extend from the screen toward the image pick-up device and to be located outside the area surrounded by lines connecting all or part of the screen and the image pick-up device, to block outside light, the image pick-up device, to take pictures of images on the screen projected by at least one of the plurality of projectors and, a calibration device which calibrates the conditions for projection of the projectors, based on image data obtained from the picture-taking results.
The image calibration method of this invention is a method for calibrating images by using a plurality of image projection devices (projectors) to project a plurality of images onto different positions of a screen by, and using an image pick-up device to take pictures of the images thereby formed on the screen, comprising the steps of providing a shielding member which shields external light, so as to extend from the screen toward the image pick-up device and to be located outside the area surrounded by lines connecting all or part of the screen and the image pick-up device, projecting a plurality of images at different positions on the screen by the plurality of projectors, taking pictures of images on the screen projected by at least one of the plurality of projectors, by using the image pick-up device, calibrating the projection conditions of the image projection devices based on the image data obtained from these results, and, after taking pictures using the image pick-up device, removing the shielding member from the image area on the screen on which images are displayed and from the space located in the normal direction of this image area.